A, B, and C are 3 angles in triangle ABC then sin(A+B)=?

(a) sinA (b)sinB (c)sinC (d)cosC (e) -sin(A+B)

1 Answer
Jul 12, 2018

sin(A+B)=sinCsin(A+B)=sinC

Explanation:

We know that , in triangleABCABC

A+B+C=piA+B+C=π

=>A+B=pi-CA+B=πC

So,

sin(A+B)=sin(pi-C)toII^(nd)Quadrant=>sinC >0sin(A+B)=sin(πC)IIndQuadrantsinC>0

=>sin(A+B)=sinCsin(A+B)=sinC

.........................................................................................................................

Please Carefully, see the image given below to understand the quadrant.

Compare with color(red)( :pi-theta toII^(nd)Quadrant.:πθIIndQuadrant.

enter image source here